Diesel engine particle filter

ABSTRACT

A diesel particle filter for lowering the emission of particles contained in the exhaust gas of a Diesel engine, is disclosed with the impaction surface of the diesel particle filter is developed such that binding forces of the ash to filter is lowered. Therefore, the adhesion of noncombustible ash particles occurs, if at all, on the impaction surface of the diesel particle filter at only with such binding forces that more the ash particles can be removed from this surface of the diesel particle filter with a fluid and/or by vibrational effects.

CROSS REFERENCE APPLICATIONS

[0001] This application claims priority from German application no. 20117 862.1 filed Nov. 6, 2001.

FIELD OF INVENTION

[0002] The present invention relates to a diesel particle filter forlowering the emission of particles contained in the exhaust gas of adiesel engine. The invention further relates to a diesel engine with anexhaust gas system and a diesel particle filter disposed in the exhaustgas system.

BACKGROUND OF THE INVENTION

[0003] Diesel particle filters are applied in exhaust gas systems ofdiesel engines to retain the soot particles contained in the exhaustgas. The soot particles contained in the exhaust gas flow duringoperation of the diesel engine accumulate on the impaction-side of thediesel particle filter. In order to prevent the increase of counterpressure in the exhaust gas, the accumulated soot is removed byoxidation within the scope of a combustion process at regular timeintervals or as a function of the exhaust gas counter pressure. In thisway a diesel particle filter can be regenerated.

[0004] However, among the soot particles deposited on the surface of thediesel particle filter are some which are not combustible and whichremain as noncombustible, inorganic components during and after suchfilter regeneration. Within the scope of the following explanationsthese components are referred to as ash. The ash is retained on thesurface or in the porous filter body.

[0005] Over the operating life of the diesel engine and/or its dieselparticle filters increasingly more ash accumulates on the impaction-sidesurface of the diesel particle filter. This causes an undesirableincrease of the exhaust gas counter pressure. For this reason the dieselparticle filter must be freed of these ash deposits at regularintervals. For example, DE 41 34 949 C2 or also DE 199 59 955 A1 proposefor cleaning such a diesel particle filter to provide access to thediesel particle filter in the exhaust gas system both in front of andbehind the filter. Directions used are in referenced to the direction offlow of the exhaust gas. Through the access a fluid can be introducedinto the exhaust gas system to flow through the diesel particle filtercounter to the direction of through flow of the exhaust gas and to bedrawn off again through the opening located at the impaction-side infront of the diesel particle filter. Through this cleaning stream theash is said to become detached from the impaction-side surface of thediesel particle filter and be taken out of the exhaust gas system. Thefluid employed can be a liquid or gaseous phased substance.

[0006] Within the cited prior art it is also proposed that the dieselparticle filter is taken out of the exhaust gas system and subsequentlybe freed of the ash deposits in corresponding cleaning baths. However,problematic in the known methods is that the cleaning of the dieselparticle filter is insufficient and incomplete. As a rule, ashaccumulations remain in the form of patches.

[0007] Building on this discussed prior art, the present inventiondiscloses a diesel particle filter that utilizes conventional cleaningmethods and obtains a better cleaning of a diesel particle filter of ashdeposits.

[0008] In the present invention the impaction surface is developed suchthat the surface has a low binding force to the ash particles. Thisresults in the adhesion of ash particles on this surface of the dieselparticle filter occurs, at most, only with such binding forces that theash particles can be removed from this surface of the diesel particlefilter with a fluid and/or through vibrational action.

SUMMARY OF THE INVENTION

[0009] The primary aspect of the present invention is to provide adiesel particle filter which has an impact surface which allows for theeasy cleaning of ash off the impact surface of the filter.

[0010] Other aspects of this invention will appear from the followingdescription and appended claims, reference being made to theaccompanying drawings forming a part of this specification wherein likereference characters designate corresponding parts in the several views.

[0011] In the diesel particle filter of the present invention at leastits impaction-side surface is developed such that ash particles arecapable of adhesion to its surface only with such binding forces—if atall—that the ash particles can be readily removed again from the dieselparticle filter by blowing a fluid in the counter flow direction orother known removal methods.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a cross sectional view of a Diesel particle filter 1.

[0013] Before explaining the disclosed embodiment of the presentinvention in detail, it is to be understood that the invention is notlimited in its application to the details of the particular arrangementshown, since the invention is capable of other embodiments. Also, theterminology used herein is for the purpose of description and not oflimitation.

DETAILED DESCRIPTION OF THE DRAWINGS

[0014] Referring first to FIG. 1, a diesel particle filter 1 is disposedin the exhaust gas flow of a diesel engine in a manner not furtherrepresented. Arrows identify the direction of flow of the exhaust gas.The impaction-side surface of the diesel particle filter 1 is coatedwith a separating layer 2. The separating layer 2 is porous in order forthe exhaust gas to flow through the layer 2 and into filter plates 3 ofdiesel particle filter 1. FIG. 1 depicts the diesel particle filter 1with an ash layer 4 deposited on the separating layer 2 before thecleaning of the filter 1.

[0015] The separating layer 2 reduces the binding forces between the ash4 and the filter plates 3 of the diesel particle filter 1, compared tothe binding forces that would occur if the ash layer were to adheredirectly on the surface of the filter plate 3. The binding forces arelowered far enough that the separating layer 2 and the adjacent ashlayer 4 can readily be detached from the filter plates 3 by applying afluid or other known removal method. The diesel particle filter 1 cantherefore be cleaned with the conventional counter flow fluid technique.FIG. 1 also shows clearly that when the separating layer 2 is decomposedthrough the use of a fluid, for example a gas, the ash layer 4 isreadily removed with the separating layer 2 from the diesel particlefilter 1 or its filter plates 3.

[0016] Binding the ash particles accumulating on the impaction-sidesurface of the filter plates 3 with one another such that the detachmentof the ash layer 4 is facilitated can also be used to carry out thecleaning of the filter surface of the diesel particle filter. Theconnection of the ash particles with one another can take place bybaking, sintering or conglomeration by adhesion of the ash particles.For example adhesive agents can be applied as a vapor onto the ash layeror the filter with the ash layer can be immersed into a thin-bodiedcuring composition. Through additional thermal treatment curing of anash layer impregnated with a binding agent the adhesive agent can beimproved and accordingly detachment from the filter can be facilitated.Sintering of the ash particles to form an ash layer can take place in aprocess completed externally.

[0017] In order to further improve the cleaning of the filter anadditive can be added to the fuel, to the motor oil, the intake airand/or to the exhaust gas flow to further reduce the adhesion of the ashparticles to one another and/or to the impaction-side surface of thediesel particle filter.

[0018] Such an additive can, for example, be injected via a deviceassociated with the exhaust gas system. The additive is turbulentlymixed with the soot particles in the exhaust gas flow and either forms achemical compound with the soot particles or is deposited together withthese and which releases its adhesion-reducing properties during sootcombustion.

[0019] The separating layer can be made of oxides of Si, Mg, Al, Caand/or Fe, a carbonate, preferably Ca, or a sulphate or a nitrate. Thesesubstances may be applied individually or as a combination of one ormore substances.

[0020] A low binding surface can be developed as a separating layer orseparating medium in order to attain adhesion reduction or bindingforce-reduction due to a material applied. Other methods to achieveadhesion reduction are by the specific nano-structures of such aseparating layer and/or the filter surface itself. Adhesion reducingseparating layers can be applied in different manner on theimpaction-side surface of the diesel particle filter, for example theapplication can take place by deposition out of a solution or asuspension. This layer can also be applied with the aid of an aerosol oralso by a sol-gel method.

[0021] In a further embodiment of the invention the impaction-sidesurface of the diesel particle filter can be smoothed by a smoothingprocess to significantly reduce the effective surface on which ashparticles can adhere. This smooth or smoothed surface can additionallybe coated with a binding force-reducing layer.

[0022] In a further embodiment of the invention the impaction-sidesurface of the diesel particle filter can be coated with a separatinglayer, whose chemical binding properties can be affected. Such an actiononto the chemical binding properties of such a layer can take placethrough a supplied fluid by which the layer applied onto the dieselparticle filter is broken down and removed together with the ashaccumulated thereon. When employing such a diesel particle filter, thebroken down layer must be applied anew after such a cleaning. Thereforethe applied layer functions as a separating layer within the originalmeaning of the word.

[0023] According to a further embodiment of the invention the removal ofthe ash particles through mechanical vibration effects is provided,which is possible by disposing an ultrasound head on the diesel particlefilter, for example.

[0024] Although the present invention has been described with referenceto preferred embodiments, numerous modifications and variations can bemade and still the result will come within the scope of the invention.No limitation with respect to the specific embodiments disclosed hereinis intended or should be inferred. Each apparatus embodiment describedherein has numerous equivalents.

I claim:
 1. A diesel particle filter for lowering the emission ofparticles contained in the exhaust gas of a Diesel engine, wherein aimpaction surface of the diesel particle filter is developed such thatadhesion of noncombustible ash particles occurs on this surface of theDiesel particle filter at most only with such binding forces that theash particles can be removed from the impaction surface of the dieselparticle filter with a fluid and/or by vibrational effects.
 2. Thediesel particle filter as claimed in claim 1, wherein the impaction-sidesurface of the diesel particle filter has a binding force-reducedsurface with respect to the binding forces of the ash particles with thediesel particle filter.
 3. Diesel particle filter as claimed in claim 2,wherein the binding force-reduced surface comprises nano-structures forthe adhesion reduction.
 4. Diesel particle filter as claimed in one ofclaims 1 to 3, wherein the impaction-side surface of the Diesel particlefilter has largely a smooth surface.
 5. Diesel particle filter asclaimed in claim 4, wherein the impaction-side surface of the Dieselparticle filter is smoothed by a smoothing process.
 6. The dieselparticle filter as claimed in claim 1, wherein the impaction-sidesurface of the diesel particle filter is coated with a separating layerwhich can be affected with respect to its chemical and/or physicalbinding properties.
 7. The diesel particle filter as claimed in one ofclaims 1 to 3, wherein the diesel particle filter in operation is usedwith an additive which is added to one or more of a fuel, a motor oil,an intake air and/or an exhaust gas flow, during the operation of thediesel engine, the additive functioning to lower the adhesion of the ashparticles to one another and/or to the impaction-side surface of thediesel particle filter.
 8. The diesel particle filter as claimed claim4, wherein the diesel particle filter in operation is used with anadditive which is added to one or more of a fuel, a motor oil, an intakeair and/or an exhaust gas flow, during the operation of the dieselengine, the additive functioning to lower the adhesion of the ashparticles to one another and/or to the impaction-side surface of thediesel particle filter.
 9. The diesel particle filter as claimed claim5, wherein the diesel particle filter in operation is used with anadditive which is added to one or more of a fuel, a motor oil, an intakeair and/or an exhaust gas flow, during the operation of the dieselengine, the additive functioning to lower the adhesion of the ashparticles to one another and/or to the impaction-side surface of thediesel particle filter.
 10. The diesel particle filter as claimed claim6, wherein the diesel particle filter in operation is used with anadditive which is added to one or more of a fuel, a motor oil, an intakeair and/or an exhaust gas flow, during the operation of the dieselengine, the additive functioning to lower the adhesion of the ashparticles to one another and/or to the impaction-side surface of thediesel particle filter.
 11. A diesel engine with an exhaust gas systemand a diesel particle filter disposed in the exhaust gas system, whereina fuel, a motor oil, an intake air and/or an exhaust gas flow had anadditive is added functioning to lower during the operation of thediesel engine the adhesion of ash particles to one another and/or to animpaction-side surface of the diesel particle filter.
 12. Diesel engineas claimed in claim 7 or 11, wherein the exhaust gas system comprises adevice by which during operation of the diesel engine an additive can beintroduced which lowers the adhesion of the ash particles on theimpaction-side surface of the diesel particle filter.
 13. The dieselparticle filter of claims 1, 2, 3 or 6, wherein the impaction side ismade of one or more of the group consisting of the oxides of Si, Mg,AL., Ca, Fe, a carbonate, a sulphate or a nitrate.